1. Field of the invention
The present invention relates to a data processing system employing portable cards and operating stations. It is applicable in particular to the banking and commercial sectors, and/or to control and security systems.
Although the forms which such cards take may vary widely and may encompass, for example, cards in the true sense, rings, keys, tickets, slips, etc., for the sake of simplicity the term "card" will be used herein and is indeed the applicable term in the majority of cases, although it should be appreciated that such use does not imply any limitation of the invention.
2. Description of the Prior Art
Portable card systems are becoming increasingly popular. Such systems comprise data processing means which consists of a plurality of individual cards and at least one shared or common operating station which is generally positioned at a fixed location. Each card comprises, in essence, means for processing data and at least one memory in which is recorded a confidential identity code known only to the rightful holder of the card. The operating station includes means for processing data from the card, together with manual control means, usually formed by a keyboard. With such a system, the holder of a card is able to perform certain monetary or accounting operations the most frequent of which are the issuing of bank notes and the keeping of an account. For this, it is merely necessary for the holder to insert his card in an operating station and then for him to identify the desired operations using the keyboard. These operations can only take place if the user of the card is able to supply the confidential code corresponding to the card being used. This preliminary checking or identification operation enables frauds to be avoided in the event of the card being lost or stolen.
A system of this kind must therefore incorporate a comparator member capable of comparing the code stored in the card with the code transmitted from outside by the user of the card. This comparator member could be situated in the operating station, but it is preferable for it to be arranged in the card to enable it to be compared with the code fed in so as to avoid the necessity of transferring the identify to the exterior, which would diminish the security of the system against fraudulent use.
Portable cards are known in which the data-carrying medium is formed by one or more magnetic tracks. They are for example what are termed "blue cards." In these cards, items of data are represented by the magnetizations exhibited by a plurality of magnetic zones. Generally, the items of data are read, and possibly fresh items of data are written, as the data-carrying medium passes in front of magnetic read and write heads.
Cards of this kind are described, for example, in French Pat. No. 1114901 entitled "Accounting Machines," granted on Dec. 26, 1955.
Cards employing magnetic tracks have many disadvantages. First of all they offer only a small storage capacity. Secondly there is a danger of losing the data recorded, in particular if they are acted on by stray magnetic fields or excessive heat. Finally, and most important, they do not protect against fraudulent use, since it is possible for an expert to detect the confidential code contained in the magnetic track and then to make illicit use of the card for his own advantage.
Attempts have therefore been made to produce portable cards employing non-magnetic data-carrying media which offer greater storage capacity and which make it far more difficult for the secret of the code to be broken. To this end "electronic" cards have been proposed. These are cards in which the code is stored by means of electronic semiconductor circuits. Such cards may, for example, make use of programmable read only memories (PROM).
French Pat. No. 2139258, entitled "Data Cards," granted Dec. 11, 1972 corresponding to U.S. Pat. No. 3,702,464, discloses a card incorporating a memory formed by a matrix of semiconductor diodes. French Pat. No. 2180349, entitled "Device for Identifying a Plurality of Persons Individually," granted Oct. 29, 1977, discloses a card employing a memory produced from integrated circuits of the metal oxide semiconductor (MOS) type.
Reference may also be made to more recent French patent applications and in particular to application No. 74.10191 entitled "Method and Arrangment for Electronic Control," filed Mar. 25, 1974, and application No. 75.14807 entitled "System for the Confidential and Personalized Transfer and Storage of Data Using Independent Portable Electronic Articles." Both these applications disclose cards in which the data carrying medium is formed by a monolithic semiconductor circuit produced by integrated circuit techniques.
As stated in application No. 75.14807, it appeared advantageous for magnetic carrier mediums to be replaced by electronic semiconductor devices because when compared with other read only memories such as magnetic cassettes, floppy discs, etc., monolithic read only memories of the semiconductor type are more reliable, they are smaller in size, require no mechanical movement for reading or writing, are insensitive to magnetic fields, and are difficult to counterfeit and fraudulently use, i.e. a potential fraudulent user has to employ complicated electronic means to alter the state of a read only memory of the semiconductor type.
Although electronic devices of this nature have proved satisfactory in certain respects, they still suffer from disadvantages. For example, the detection of confidential identity code, although difficult, is by no means impossible to an electronics expert. Also, semiconductor memories which are "read only" memories, only permit reading operations.